This invention relates to accessories for rotary tools. More specifically, this invention relates to mechanisms or chucks for retaining, preferably round shanked tool bits or accessories for preferably unidirectional rotary tools such as those sold under the Dremel, Black & Decker or Craftsman trademarks that offer conventional methods to achieve tool change and holding capability.
Due to problems associated with gripping and driving tool bits with round shanks, one known solution is via a collet and a tightening nut, which is rotated to secure the shank of the tool bit. The shortcoming of this design is the cumbersome and time-consuming tool changes. Generally, a spindle of the rotary tool is locked in one position and held there. A separate tool; such as an open-ended wrench, is used to engage the nut to loosen it from the collet. The tool bit or accessory is then removed from the tool. To install another accessory, the reverse operation is performed. The spindle is locked into place again and held in that position. The shank of the tool bit or accessory is inserted into the collet and the nut is tightened. An open-ended wrench is used to securely tighten the shank in the collet. As well as being too time-consuming, this method is also inconvenient since a user grasps the tool and locks the spindle in place, while simultaneously inserting the accessory into the collet and tightening the nut around the shank of the accessory. This method also requires the use of a separate tool to tighten and loosen the shank of the accessory from the collet.
Another method of attaching accessories to rotary tools is by using a three-jaw chuck. In this method, again, the spindle of the tool is locked into position, while the chuck is tightened on the shank of the tool bit or accessory. In some cases, a separate tool, such as a wrench or Allen key, is used to tighten or loosen the chuck once it has been finger-tightened. This method again requires the user to change the tool bit or accessory using both hands when there are three areas the user must contact: the spindle, the shank, and the chuck.
There is a need for a mechanism that provides quicker tool changing yet equals or betters the mechanism's capability to hold the tool in its operation. There is also a need for a mechanism that does not require any extra tools for operation.
It is, therefore, desirable to provide an improved chuck for a use with a rotary tool.